Create and save preset nodes in the 2.81 blender, for example for material and texture
So you mean, you need a technique which can help you make a library of your node setups so you just have to click to import.

There are some free/paid addons out here to do this action. 

https://blendermarket.com/products/node-kit (paid) 
https://blendermarket.com/products/nodecustombuilder  (FREE available but can also be purchased to donate to the developer) 

If you want to achieve this natively in blender without any addons, 
Just save your favorite node setups in your dedicated node group blend file.

Whenever you need that node setup or material, 
You can go to file > append > your dedicated blend file and apeend node group or material you like